ok. because come across several little problems and questions in my [first] controlling-pwm-with-Arduino project, I'll ask them all

so first of all: I want program a composition in pwm for both dc motors and big light [say up to 100W or more].

1-- motor: for the dc motor I build an extra circuit for separate power supply according to a circuit which is provided quite a lot the internetlike described here http://www.thebox.myzen.co.uk/Tutorial/Power_Supplies.html[+ I'd like to add a resistor between source and ground.]problem: it works [for a long period] without the 1k resistor, with it doesn't do anything. Do I need a lower resistor here? Do I demolish the Arduino and blow up the FET if I don't use a resistor?

2-- I would like to control 3 dc motors. Do I need 3 separate power supplies? [I have 12V/1A amps now]

3-- grounding. How do I make a grounding so that they don't affect eachother? Do I need to make a star grounding for these 3 motorcircuits? Is grounding only direct to the Arduino oké or does it need a piece of metal to drain?

4-- Light. Together with the motors I want to make a dimming composition for light. 3 times again. I'm not exact sure what kind of light - probably halogen, high Watt. To also do this with Arduino I think I found a nice solution for this: a Velleman K8064 kit and a capacitor will do http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1266079091is it smart to use the same Arduino as for the motors for this?someone has experience with big lights and this Velleman?

No that one is not as good as the first one as it is not rated for 5V, therefore you would have to drive it with at least a 10V gate signal. To do that from an arduino you would have to use a transistor ahead of the FET.